The word "tightlipped" means someone who is unwilling to speak or reveal information. Some synonyms for this word include reserved, reticent, close-mouthed, secretive, uncommunicative, guarded, taciturn, silent, and unforthcoming. These words describe individuals who are not forthcoming or willing to share information with others. They may be shy, cautious, or mysterious in their communication style. These words are often used to describe people who have secrets they do not want to reveal or who are hiding something. When someone is tightlipped, it can be challenging to get them to open up and share their thoughts or opinions.